Round hand stamps have been commercially available for many years. Such round hand stamps typically include a generally cylindrical configuration. Such hand stamps may be of the self-inking or pre-inked typed.
Self-inking hand stamps typically include an invertible stamp carrying platen and ink pad arranged within a frame. The platen may be connected to an impressible case which is slidably mounted on the frame.
The marking structure (i.e., the actual stamping member) of self-inking hand stamps are made of rubber or the like. They must be placed in contact with a source of ink, such as an internal ink pad, when the hand stamp is in a rest position. The ink pad may be permanently arranged within the hand stamp or may be removable.
Rubber marking structures used in self-inking hand stamps have a printing surface, which is typically arranged in contact with the ink pad when the hand stamp is in a rest position. The printing face of the marking structure is then typically moved and inverted along with a platen on which it is mounted through 180 degrees until it comes into contact with the desired surface to be printed—i.e., when the hand stamp is depressed into a printing position.
One brand of high-quality self-inking hand stamps is manufactured and sold by M&R Marking Systems, Inc. under the trademark IDEAL®. Such self-inking hand stamps are discussed in prior art patents owned by M&R Marking Systems, Inc. including U.S. Pat. Nos. 5,649,485; 4,852,489; and 4,432,281.
The self-inking hand stamps disclosed in the '485, '489 and '281 patents have provided important commercial improvements in the hand stamp industry. Such improvements include, for example, a removable ink pad holder having re-inking ports on the back thereof; the ability to quickly and neatly replenish the ink supply of an associated ink pad; the ability to grasp the hand stamp from any direction; and advantages relating to displaying indicia information to be imprinted by the hand stamp.
While the foregoing self-inking hand stamps have been commercially successful and provided significant advantages, a need still exists for further improvements in self-inking and pre-inked hand stamp devices.
Pre-inked hand stamps include microporous marking structures, which are typically made of various polymeric materials and resin. These materials may comprise thermoplastic resin or other open cell compositions, such as specially formulated foam having a large quantity of microscopic pores. The microporous marking structure may be impregnated with ink or other suitable marking fluid during the manufacturing process or after it is manufactured.
Pre-inked hand stamps differ from self-inking hand stamps in that they do not need to include a separate ink pad as a source of marking fluid. Thus, pre-inked hand stamps can be used to create numerous ink impressions without requiring the user to introduce additional ink into the marking structure. This is possible due to the microscopic size of the pores, which allow the ink initially retained therein to escape at a controlled rate.
One brand of high-quality pre-inked hand stamps is manufactured and sold by M&R Marking Systems, Inc. under the trademark ROYAL MARK®. These pre-inked marking structures are made from ROYAL MARK® brand gel, which comprises a mixture of thermoplastic resin and ink. Another well known brand of high-quality pre-inked hand stamps is marketed by M&R Marking Systems, Ink under the trademark OPTIMARK®. The OPTIMARK® brand hand stamps include a microporous foam material as the marking structure.
Yet another brand of high-quality pre-inking hand stamps is manufactured and sold by M&R Marking Systems, Inc. under the trademark ULTIMARK®. The ULTIMARK® brand hand stamps includes a microporous foam material, which has been impregnated with ink during the manufacturing process, as the marking structure.
Self-inking and pre-inked hand stamps exist in many geometric shapes and sizes. For some applications, it is desirable for the hand stamps to have a generally cylindrical configuration. Such cylindrical hand stamps are known as round hand stamps. When the round hand stamps are self-inking stamps, they are known are known round self-inkers.
Efforts have been made in designing round self-inkers to securely mount the case of the hand stamp to the frame. Typically, the platen is also secured to the case and is movable along with the marking structure secured thereon from a rest position, where the marking structure is in contact with an internal ink pad, to a printing position where the face of the marking structure becomes inverted and contacts the desired surface to be imprinted.
It is important in round self-inkers to secure the case to the frame such that the case will not become dislodged in the event that the hand stamp is accidentally dropped or a twisting force is applied when the hand stamp is operated. To meet this need, it is known for the case of the hand stamp to include ribs and the frame of the hand stamp to include cooperating grooves (e.g., slots) in which the ribs are arranged. In such an embodiment, the case is free to slide longitudinally along the frame as it is depressed during operation of the hand stamp. While it is desirable for the case to be fully slidable in the longitudinal direction (i.e., typically in the vertical direction), it is undesirable for the construction of the hand stamp to be such that the case can easily become dislodged if a twisting force is applied to it.
Round pre-inked hand stamps may have the same problems, but typically secure the case to the frame in a different manner as it is not necessary for the marking structure to have the same degree of movement and inversion as is the case in self-inking hand stamps.